Fluidizing bed coking method of brown coal

ABSTRACT

For the coking of brown coal, lignite or the like there is provided a coking system which includes a coking apparatus and an associated heater from which hot air is introduced into the coking apparatus. One part of the fine grained portion of the charge mixed with gases derived from the coking process is introduced from the coking apparatus into the combustion chamber of said heater to serve as fuel therefor.

United States Patent Wenzelet al.

[4 1 June 20, 1972 [54] FLUIDIZING BED COKING METHOD OF BROWN COALWerner Wenzel, Aachen; Hans Penning, Cologne Lindenthal, both of Germany[72] lnventors:

I71] Assiguer. Rllclnlsche lh'annkulilenwerke AG, Koln,

Germany [22] Filed: April 29, 1970 [21] Appl. No.: 32,891

[ 30] Foreign Application Priority Data April 29, 1969 Germany ..P 19 21710.8

(52] US. Cl ..201/15, 201/27, 201/31, 20l/42, 201/6 [5 l Int. Cl. ..Cl0b49/10 [58] FieldofSearch "201/27, l3, l4, 15, 16,31, 201/42. 32, 36, 37.38; 110/28 J, 8; 202/121 OAL FINES 8 GASES comm; FLUIDIZED BED L COKEPRODUCT 5 a [5 6] References Cited UNITED STATES PATENTS 2,742,0014/1956 Kardaun et a] ..1 10/28 J 3,043,752 7/1962 Foch 201/31 2,595,3665/l952 Odell et al. ....i20l/3l I,64H,H56 I 111927 Mcliwen -2Ul/l4Primary Examiner-Norman Yudkoff Assistant ExaminerDavid EdwardsAttorney-Edwin E. Greigg ABSTRACT For the coking of brown coal, ligniteor the like there is provided a coking system which includes a cokingapparatus and an associated heater from which hot air is introduced intothe coking apparatus. One part of the fine grained portion of the chargemixed with gases derived from the coking process is introduced from thecoking apparatus into the combustion chamber of said heater to serve asfuel therefor.

6 Claims, 1 Drawing Figure HOT AIR COMBUSTlON HEATER (FINES 8 GASES)FLUIDIZING BED COKING METHOD OF BROWN COAL BACKGROUND OF THE INVENTIONThe economic feasibility of the manufacture of coke from fossil-typefuels is affected to a significant extent by the costs involving theirpreparatory treatment. Accordingly, it is a basic desideratum to submitthe coal, prior to coking, to as few processes as possible to keep theentire coking operation simple and economical.

In view of the above considerations, either raw brown coal, or a coallittle burdened by drying, comminuting or preforming (such aspelletizing) should be used for coking fossil-type charges. Despiteadvantageous prospects of coking raw coal, no coking processes of thistype for mass production have been developed. The reason for this mayprobably be found in the difficult pyrometric conditions required forthe coking of raw coal.

The invention is based on a known process of and an apparatus for cokingbrown coal, particularly brown coal having a relatively high watercontent, whereby the coking is performed while the coal is in aturbulent condition and the necessary heat is supplied by injecting hotgases, preferably derived from a partial combustion of the coal. Thegases obtained during the coking process are burned in a heater.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention tointroduce an improved method and an apparatus of the aforenoted type forproviding a technically and economically advantageous coking of browncoal, particularly raw brown coal, lignite or similar fuel.

Briefly stated, according to the invention, the coking apparatus isconnected with a heater from which hot air is introduced into the cokingapparatus. One part of the fine grained portion of the charge is carriedby the gases derived from the coking process into the heater to serve asfuel therefor.

The invention will be better understood and further objects andadvantages will become more apparent from the ensuing detailedspecification of a preferred, although exemplary embodiment of theinvention taken in conjunction with the sole figure schematicallyillustrating the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT O-comminuting The coking systemaccording to the invention includes a coking apparatus I having anapertured, sieve-like base 2. The apparatus I is charged at the top at 4with coking fuel such as brown coal which preferably has a grain size of30 mm. The grain size distribution is that which normally results fromcrushing raw brown coal in a conventional communiting device.

The coking system according to the invention further includes a heater 7from which heated air for combustion is taken through conduit 3 andintroduced into the coking apparatus l at 3a through the apertured base2. By virtue of the upwardly directed air flow a fluidized bed is formedwhich is supported by the apertured base 2.

The velocity of the gas through the fluidized bed is set to such a valuethat the large size coal settles on or in the vicinity of the base 2. Inthis range the coal is not exposed to the turbulent air action proper;there is merely a relatively slight mixing caused by the throughgoinggases. In an extreme case, the large-grained coal supported on base 2may form a stationary bed which, as the grain size decreases upwardly,gradually changes into the fluidized bed proper.

The velocity of the gas streaming through the coking apparatus isfurther so regulated that a major, fine-grained portion of the coal(approximately 75-95 percent of the charge) is carried by the combustiongases derived from the coking through conduit 6 and introduced into theheater 7. Approximately -25 percent of the charge remains in the cokingapparatus due to its grain size. In the heater 7 the mixture of coal andcoking gases is burned with the aid of hot air taken from the heater 7itself and introduced into its firing chamber through conduit 3b.Exhaust gases resulting from this combustion are discharged at 8.

The most advantageous velocities of the gas at different heights of thefluidized bed may be regulated in a known manner by accordingly varyingthe cross-sectional configuration of the fluidized bed. Thus, forexample, the cross section of the fluidized bed may be of a smallervalue at its base than at its upper surface.

The hot air furnished by the heater 7 to the coking apparatus at atemperature of approximately 250-450 C, burns preponderantly with thefine-grained portion of the raw coal with simultaneous heat generation.The ratio of hot air admitted through base 2 to the raw brown coalcharged at 4 is set to such a value that an average temperature of 600900 C prevails in the coking apparatus. At such temperature, a rapiddrying of the fine-grained pieces of the raw brown coal takes place, sothat the latter may be carried out of the coking apparatus at 6 by thegases in a substantially dried condition.

The coal pieces of large dimension which, as noted hereinbefore, settleat the base 2 because of their weight and constitute about 5-25 percentof the charge, are dried and degassed, whereby the degree ofdegasification and of conversion into coke are dependent on the dwellingtime of the respective coal pieces in the coking bed and on thetemperature prevailing in the coking apparatus.

The finished coke, which has a grain size of about 5- 20 mm, may betaken out of the fluid bed at 5 by known removing means (eg an augermechanism) directly from above the perforated base 2.

In order to adapt the coal taken from the coking apparatus 1 to thefiring conditions of the adjoining heater 7, the coal may be comminuted,preferably to powder form, prior to the introduction thereof into theheater. For this purpose, known comminuting apparatus such as an impactmill, may be used.

Several modifications may be effected in the aforedescribed exemplaryembodiment of the invention to adapt it to any particular type of coalor heater. Thus, instead of a fluidized bed-type coking apparatus amobile grill-type coking apparatus may be used. In such an apparatus amajor part of the coal is combusted on the grill for generating the heatnecessary to operate the heater, while a smaller part of the charge iscarried out by the grill as coke. Instead of hot air, hot gases may beblown through the coking apparatus. These hot gases may be, for example,the exhaust gases taken from the heater.

What is claimed is 1. A method of coking brown coal or the likecomprising the following steps:

A. continuously charging a coking apparatus with said coal having agrain size between 0 and approximately 30 mm,

B. introducing hot gas from a heater into said coking apparatus foreffecting coking therein,

C. introducing approximately 75-95 percent of the coal charge asfine-grained coal with and by means of coking gases from said cokingapparatus into said heater,

D. burning the coal-gas mixture introduced in said heater to obtain saidhot gas,

E. converting the approximately 5-25 percent of the charge remaining inthe coking apparatus into coke having a grain size approximately 5 20mm, and

F. withdrawing said coke from said coking apparatus.

2. A method as defined in claim 1, wherein said charge is introducedinto said coking apparatus downwardly at the upper portion thereof andsaid hot gas is introduced into said coking apparatus upwardly through abase thereof to create a fluidized bed containing said 5-25 percent ofsaid charge and to cause said 75-95 percent of said charge to be carriedinto said heater.

3. A method as defined in claim 1, wherein said hot gas has atemperature between approximately 250 C- 450 C.

4. A method as defined in claim 1, wherein the flow rate of said chargeand of said hot gas is so regulated that the temperature in said cokingapparatus is at a value between 600 900 C.

5. A method as defined in claim 1, including the step of comminuting thecoal taken out with said coking gases from said coking apparatus priorto its introduction into said heater. 5

6. A method as defined in claim 5, wherein said comminuting step effectsa reduction of the coal taken from said coking apparatus to powder sizegrains.

2. A method as defined in claim 1, wherein said charge is introducedinto said coking apparatus downwardly at the upper portion thereof andsaid hot gas is introduced into said coking apparatus upwardly through abase thereof to create a fluidized bed containing said 5-25 percent ofsaid charge and to cause said 75-95 percent of said charge to be carriedinto said heater.
 3. A method as defined in claim 1, wherein said hotgas has a temperature between approximately 250* C- 450* C.
 4. A methodas defined in claim 1, wherein the flow rate of said charge and of saidhot gas is so regulated that the temperature in said coking apparatus isat a value between 600* - 900* C.
 5. A method as defined in claim 1,including the step of comminuting the coal taken out with said cokinggases from said coking apparatus prior to its introduction into saidheater.
 6. A method as defined in claim 5, wherein said comminuting stepeffects a reduction of the coal taken from said coking apparatus topowder size grains.